1. Field of the Invention
This invention pertains to spliced strips of film such as are used in continuous-processing photographic machinery and the like. It is conventional practice in such machines to utilize a plurality of strips of film which are connected end-to-end by splices. In the event that such splices are defective, there is a danger that a splice may give way during processing and thus cause the process to be interrupted. Thus, more specifically, this invention pertains to the field of detection of such defective splices, so that defectively-spliced strips of film are not passed through such machines and subjected to further processing.
2. Background of the Invention
Devices of this type are already known. It is, for example, already known to provide a device of this sort which causes the film strips to be passed along a zig-zag path, so that in the event that a splice is improperly adhered to a strip of film it will be lifted off the film and will trip a lever or other suitable element in order to generate an error signal which can cause the movement of the film in the machine to cease.
However, certain types of defective splices would not be detected by such a machine, and could still break during subsequent processing. For example, if two strips which are spliced together are not separated by a properlysized gap, it is possible that the perforations in the strips of film would not properly engage the toothed rollers that transport the film with the result that the misalignment thus caused could result in damage to the film to be processed. Alternatively, even if the gap were properly sized, it could be that a splice is not properly centered over the gap, in which case the overlap on one side of the splice would be insufficient and the splice would have insufficient adhesion area for proper strength during further processing. This type of defect is particularly troublesome, since a splice which has entirely adequate mechanical holding power prior to processing may, during subsequent processing operations such as development, fixing and bleaching, lose enough of its strength so as to cause subsequent breakage. Additionally, it is possible that the strips themselves, because of defects caused by improper cutting, may have corners which are torn or folded over or actually overlap a corresponding corner of an adjacent strip. These defects can also result in further trouble during subsequent processes operations.
It would thus be advantageous to provide a system which would detect splicing defects of these sorts, so as to increase the likelihood that the subsequent processing operations would remain continuous and so as to prevent improperly-spliced film strips from being subjected to processing.